Well bore milling apparatus



May 28, 1963 E. H. CLARK, JR

WELL BORE MILLING APPARATUS Original Filed March 25, 1958 t il May 28, 1963 E. H. CLARK, JR

WELL BORE MILLING APPARATUS Original Filed March 25, 1958 me. WN, V mm a g E W fw Arran/16 May 28, 1963 E. H. CLARK, JR

WELL BoRE MILLING APPARATUS Filed March 25, 1958 3 Sheets-Sheet 5 Original rraeA/fs/f I'III.

States The Ipresent invention relates to `apparatus rfor milling away devices or obstructions in well bores, `and more particularly to :apparatus for milling vaway packers or plugs secured in well casings, and similar conduits, disposed in well bores.

This application is a division of my joint application with Talmadge L. Crowe `for Well Bore Milling Apparatus, Serial No. 723,839, liled March 25, 1958, now U.S. `Patent No. 3,005,493.

An object of the invention is to provide milling apparatus for cutting away la #well packer, or the like, in a well casing disposed in a well bore, in which the milling apparatus -is maintained properly centered with respect to the packer to insure its ellective operation on the packer `and to prevent the apparat-us from digging into or cutting the well casing.

A further object of the invention is to provide milling apparatus capable of cutting away a well packer, or the like, secured in well casing disposed in `a bore hole to the extent tha-t )the well packer is released rhom the well easing, whereupon the apparatus is capable `of retrieving the remaining pontion of the well packer.

This invention possesses many other advantages, and has other objects which may be made more clear-ly apparent from a consideration of a form in which it may be embodied. This orm is shown in `the drawings accompanying Vand forming par-t of the present specification. It will now be described in detail, 4for the purpose of illustrating the lgene-ral principles of the invention; but it is to be understood that such detailed description is not to be taken in la limiting sense, since the scope of Jche invention is best defined by the appended claims.

Referring to the drawings:

FIGURES l and la together .constitute a longitudinal section through an apparatus disposed in a Well casing, FIG. la constituting a lower continuation of FIG. l;

FIG. 2 is la view corresponding to FIG. l illustrating the chiseling or impacting portion Vof the apparatus in operation;

IFIG. 3 is a view similar :to FIG. la illustrating the manner of releasing the fappanatus from ya well packe-r without withdrawing the latter, or a portion thereof, from the well casing;

FIG. 4 is Ian enlarged longitudinal section chisel portion `ocE the milling apparatus;

FIG. 5 is la cross-section taken along the line 5-5 on FIG. 4;

FIG. 6 is Ia cross-section taken along the line 6-6 on FIG. 4;

FIG. 7 is tan enlarged cross-section taken along the line 7-7 on FIG. 1;

FIG. 8 is a longitudinal section through a portion of the apparatus shown in FIG. la, with parts shown in another position.

The milling or through the disintegrating apparatus A illustrated arent ice in the drawings is particularly adapted for partially or ful-ly disintegrating a well packer B, bridge plug, or the like, secured in a well casing C disposed in a well bore. The milling apparatus is adapted to be lowered in the well casing and operated therewithin by means of a tubular string D, such as drill pipe or tubing, extending to the top :of the well bore, the apparatus also being eective to retrieve at least a portion of the well packer B, or similar apparatus, as la result of its proper manipulation and elevation of the tubular string D in the well Icasing lC.

The :well packer shown by way yof example in the dnawin-gs is particularly described in United States Patent No. 2,624,412. Essentially, it includes a tubular body .10 having .an upper setting sleeve 11 slidable thereon adapted lto engage an upper set of segmental slips 12 that coact with an upper expander 13 to secure the packer to the well casing C against upward movement thereon. A lower set of segmental slips 14 ien-gages the lower portion 15 of Ithe body and -is held in ancho-ring engagement with zthe wall :of the well casing by a lower expander 16 to prevent downward movement of the well packer within the well casing. A packing unit 17, such as a rubber or rubber-like packing sleeve, is compressed between the upper and lower expanders 13, -16 in sealing engagement with the wall of the well casing and the exterior of the packer body '10, to prevent leakage of fluid around the exterior of the body and the inner wall of the iwell casing.

The well packer B may also have a lower junk catcher and dieeler portion 18, which is useful in insuring that the well packer can be lowered to the desi-red setting point in the well casing preparatory to expansion or its upper land lower slips 12, 114 and 4the packing unit 17 into engagement with the wall of the well casing. The lower portion of the body 10 has a valve seat v19 formed therein surrounding its control passage `20 adapted to be engaged by a flapper valve head 21 pivotally mounted on a hinge pin 22 suitably secured to the packer body, the valve bead being urged upwardly into engagement with its companion valve seat by a spring 23. The valve seat .19 provides :a downwardly Ifacing shoulder which .is tapered in an upward `and inward direction for coaction wit-h the milling apparatus A in retrieving the lower portion of rthe well packer, las described hereinbelow.

The milling apparatus A is capable of disintegrating the well packer B, either fully Ior partially, by either a rotary action in response .to rotation of the tubular string D, or by an impacting or chiseling action, by delivering blows through lowering of the tubular string D. As shown, lthe milling apparatus includes `an youter tubular structure, housing Ior cylinder 24, consisting of an upper sub Z5 having an upper pin `26 :threadedly secured to the lower end of the tubular string D. An intermediate housing portion 27 has its upper portion threadedly secured to the upper sub 25 and is telescoped over an inner tubular member 28, such as a kelly or mandrel. The lower portion of the outer tubular member 24 includes a chisel `device `29, the lupper head portion 30 of which is threadedly secured within the lower end of the intermediate housing 27, the upper end 31 of the head being spaced downwardly from an inwardly directed shoulder 32 on the housing to define -an internal circumferential groove 33 in which a split snap ring 3'4 is contained. This snap ring is adapted to engage either the upper side 32 of the groove or the lower side 31 of the groove.

The snap ring 34 inherently tends to contract into engagement with the mandrel 28 extending therethrough, being received within an external groove 35 in the mandrel to longitudinally couple the latter to the outer tubular member 24 for movement therewith. Thus, the snap ring 34 -is received partially in the internal groove 33 and parti-ally in the external groove 35, its lower end 36 being adapted to engage an upper cam or tapered surface 37 on the mandrel inclined in an'up-ward and inward direction. The imposition of a sufficient downward force on the outer tubular member 24 will cause it to force the lower tapered end 36 of the snap ring against the upper cam surface 37, which will expand the ring 34 outwardly and thus permit the outer housing 24 to move downwardly very rapidly over the inner mandrel 28, for a purpose described hereinbelow. Upward movement of the housing 24`relative to the mandrel 28 will cause a lower tapered surface 38 on the mandrel to engage the snap ring 34 and expand it outwardly.

The upper cam surface 37 has a relatively shallow taper, so that a comparatively great force is required to expand the ring 34 outwardly and to permit downward movement of the outer tubular member 24 over the mandrel 28. However, the lower cam surface 38 has a comparatively steep taper, so that a much lesser force is necessary to expand the snap ring 34 and permit the outer, upper tubular member 24 to shift back over the mandrel to its initial upper position, such as shown in FIG. l.

rIlhe chisel portion 29 of the apparatus includes the chisel head 30` described above, from which depends a plurality, such as three, of circum-ferentially spaced chisellike teeth l40 terminating in chisel edges 41. Between the chisel teeth 40, the head has longitudinal grooves or passages 42 therethrough to permit upward movement of the cuttings and drilling fluid therethrough. The head 30 ofthe chisel has a non-circular, such as a hexagonal, bore 43 slidably tting a companion external non-circular configuration 44 on the mandrel below the lower tapered surface 38. This hexagonal and non-circular shape 44 on the mandrel extends downwardly and through a lower milling cutter 45 having a companion non-circular or hexagonal bore or socket 46 therethrough, to rotationally couple the mandrel 2S to the milling cutter.

The milling cutter 45 is prevented from moving axially of the mandrel 28 by a lower llange 47 on the cutter engaging a downwardly directed shoulder 48 on the mandrel, the ange 'being clamped against the shoulder by a pilot portion 49 of the apparatus adapted to extend into the bore 20 of the well packer B. This pilot portion includes an upper sub 50 threaded on to the lower portion of the mandrel v28 and engaging the milling cutter flange 47. The milling cutter itself has circumferentially spaced cutter blades or teeth 51 thereon provided with hard facing material 52 on their leading faces and adapted to engage and operate upon the packer setting sleeve 11, the packer body 10, slips 12, 14, expanders 13, 16, packing sleeve 17, and, for that matter, all portions of the well packer B, or other device, disposed in the well bore. It is evident that the rotation of the tubular string D is transmitted through the outer tubular member 24 to the mandrel 28 by Virtue of the slidable spline connection 43, 44 therebetween, and from the mandrel 28 to the milling cutter 45 by virtue of the slidable spline connection 44, 46 therebetween.

The chisel portion 29 of the apparatus is normally disposed a substantial distance above the milling cutter portion 45 and is retained in such elevated position by the fitting of the snap ring 34 in the extemal circumferential groove 35. However, when the snapring 34 is released, as by imparting sufficient downwardforce on the tubular string D and the outer tubular member 24, the chisel 29 will shift downwardly rapidly, its teeth 40y being arcuately displaced with respect to the milling cutter teeth 51, so as topass bet-Ween the latter and strike the well packer B.

The pilot portion 49 of the milling apparatus includes the upper sub 50 referred to above, this upper sub being 2feet 69 of the spring legs 62.

threadedly secured to the upper portion of an extension sleeve 55, the lower end of which is threadedly secured onto a lower pilot mandrel 56. A lock nut 57 is also `threaded on the lower pilot mandrel, engaging the lower end of the extension sleeve 55, and also serving as a spring seat for the upper end of a helical compression spring 58 encircling the pilot mandrel 56 and bearing at its lower end against a catch sleeve 59. This catch sleeve can move downwardly of the mandrel to the extent limited by er1- gagernent of its inwardly directed ange 60 with an upwardly directed shoulder61 on the mandrel. It includes a plurality of circumferentially spaced depending springlike legs 62 normally urged by the helical compression spring 58 downwardly into engagement with a holding and safety member 63 in the form of a sub threaded onto the lower portion of the pilot mandrel 56 by means of a lefthand threaded connection 64. The lower ends 65 of the spring-like legs 62 are normal to the axis of the apparatus engaging a companion shoulder 66 at the upper portion of the holding sub 63. Such normal surface 66 of the holding sub terminates at an upward and inwardly inclined holding surface 67 adapted to engage companion inclined surfaces 68 at the lower portions of the spring legs, so as to hold such legs in an outward direction. When disposed in such outward direction, lower foot portions 69 of the legs are adapted to engage the catch shoulder or valve seat 19 of the well packer, coupling the pilot mandrel 56 to the body of the tool. When the pilot mandrel 56 and safety sub 63 are moved down through the packer B, the safety sub will engage the apper valve head 21 and swing 1t down-wardly from its seat 19 completely to one side of the passage 20 through the packer body 10.

The safety and holding sub 63 has a safety screw 70 threaded radially therein and extending into an elongate groove 71 in the lower portion of the safety mandrel 56. Such safety screw is provided to prevent complete unthreading of the safety sub 63 from the mandrel 56, inasmuch as the safety screw will engage the lower flange portion 72 of the mandrel.

When it is desired to disintegrate or mill up the well packer B, or a portion thereof, which is anchored in packed-off condition in the well casing, the milling apparatus A is secured to 'the lower end of Ithe tubular string D and is lowered in the well casing C. At this time the snap ring 34 is disposed in 4the mandrel groove 35 and will Icouple the outer tubulatt member 24 to the mandrel 28 for joint longitudinal movement. The hold- -mg and safety sub 63 moves into 4the packer body passage 2t), lfollowed by the pilot mandrel 56, pilot extension sleeve 55, land upper pilot sub 50, the spring legs 62 engagrng the upper end 4of the body 10 and being shifted upwardly of the pilot mandrel 56 against the force of the compression spring 58 and inwardly, such inward action being assisted by the tapered lower ends 75 of the The spring legs will then slrde along the wall of the body passage 20 until they are disposed below the catch shoulder or valve seat 19 of the body 10, whereupon they can shift outwardly again, being forced down along the upper tapered portion 67v ofthe holding and safety sub 63 by the helical compression spring 58 and into engagement with the normal shoulder 66 of the holding sub, such as shown in FIG. la. 'I'he safety subY 63 will have shifted the flapper valve head 21 away from its seat 19 and to one side of the body 10 of the tool.

With the spring legs v62 in the position illustrated in PIG. la, the milling cutter blades 51 Will engage the upper end of the setting sleeve portion 11 of the well packer B, and the milling action can commence. The pilot portion 49 of the milling apparatus will appropriatelyv center the cutter blades 51 relative to the packer tool B, keeping the cutter blades away from the wall of the well casing C, preventing them from digging into the latter. The radial extent of the'cutter blades is such as to clear the inner wall of the casing C, but to extend outwardly beyond the exterior of the setting sleeve 11. The pilot portion 49 of the apparatus purposely makes a slightly loose iit in the bore 20 of the well packer, since it is found that the milling cutters operate more effectively with such relatively loose iit. For example, the maximum diameter of the pilot portion 49 might be about one-eighth of an inch less than the minimum inside diameter ofthe body of the well tool.

The tubular string D is rotated, rotating the outer tubular member 24 and the mandrel 28, because of the non-circular connection 43, 44 between the chisel and the mandrel. The rotation of the mandrel 28 is transferred through the non-circular connection 44, 46 to the milling cutter 45, the cutter teeth 51 being rotated while being urged against the setting sleeve 11 by `a suicient downward force imposed on the tubular string D, the outer tubular member 24 and the mandrel 23. The snap ring 34 will not be cammed out of the mandrel groove 35 by the usual downward force imposed thereon and necessary to provide a cutting action of the blades S1 on lthe packer parts, since the force required to release the snap ring is quite extensive. For example, a downward force of 10,000 pounds may be necessary, before the snap ring 34 is cammed out of the groove 35 and permit downward movement of the outer tubular member 24 along the mandrel 28. With the proper downward force imposed on the cutter blades 51 and with the apparatus rotating, the cutter blades will mill away the packer portions. The cuttings are circulated out of the hold by pumping drilling fluid down through the tubular string D, the outer tubular member 24 and mandrel 28, the fluid discharging through ports S0 in the lower portion of the mandrel opposite the cutter blades 51, to flush the cuttings from the cutting region upwardly around the exterior of the tool A and tubular string D back to the top of the well bore.

The drilling action continues by rotating the :apparat-us B at a proper speed and with a proper down weight posed on the cutter blades 51, until the setting sleeve 11 4is disintegrated, as well as the upper slips 12, upper expander 13, packing sleeve 17, and the lower exp-ander 16, slips 14 and body 10 of the tool, down to the position in which the lower slips 14 are no longer backed up by the lower expander, which will permit the remaining parts of the lower slips 14 to release from Ithe well casing. When this occurs, the remainder ofthe packer body 10 will probably drop down along the pilot mandrel 56 until the catch shoulder 19 engages the feet 69 at the lower ends of the spring legs 62. It is unnecessary to perform any ladditional mill-ing action on the well packer, since the tubular string D need merely be elevated to raise the outer tubular member 24, mandrel 2S and pilot mechanism 49, '59, and lower portion of the well packer in the well casing, to withdraw the apparatus `and the lower well packer portion :to the top of the hole, leaving the well casing C free from any packer material therewithin.

In the event that the milling cutters S1 may not be milling up the well packer effectively, most portions of which are normally made of readily drillable material, such as cast iron, the destruction or breaking of the well packer can be effected through use of the chisel teeth 40 that have staggered relation with respect to the milling teeth 51. Thus, the imposition of a sucient downward force on the tubular string D and the outer tubular member 24 will press the snap ring 34 against the upper cam surface 37, which tends to urge the snap ring out of the mandrel groove 35. When the downward force exceeds a predetermined value, which, for example, may be 10,000 pounds, the snap ring 34 is expanded out of the groove 3S, whereupon the outer tubular member 24 and its chisel teeth 40 are propelled downwardly at a rapid rate, the chisel teeth moving downwardly between the milling cutter teeth 51 'to strike a comparatively great impact blow upon the well packer, ltending to break the latter into pieces. Fluid may be circulated down through the tubular string D and the apparatus to wash away any pieces that have been broken away by the chisel teeth.

Repeated blows can be struck by the chisel tool 29 on the packer B by recocking the Iapparatus. This is done with comparative little force imposed on the tubular string D yand the outer tubular member 24, since elevation of the apparatus will move the spring legs 612 up against the catch shoulder 19 to prevent upward movement of .the pilot portion 49 of the apparatus and the mandrel 28. The outer tubular member 24 is moved upwardly along the kelly or mandrel 28, the snap ring 34 engaging the steeply tapered cam surface 33 which expands i-t outwardly until the outer tubular member 24 is returned to its uppermost position, as determined by engagement of a housing -shoulder with the outwardly extending ange l91 at the upper end of the mandrel 28. The force required to recock the apparatus, that is, to place the snap ring 34 back in its external groove 35, as has been stated above, is relatively small. Whereas the angle of taper on the upper cam 37 might require about 10,000 pounds to expand and release the ring, the very steep taper on yt-he lower cam 38 is such that only about pounds, or even a lesser force, is necessary to shift the outer tubular member 24 back upwardly along the hexagonal kelly 28 to a position in which the snap ring 34 can move back into the external groove 35.

Another jarring blow can now be imposed on the well packer lB by imposing a downward torce on the tubular string D which will lirst reengage the cutter blades 51 with the existing upper end of the well packer. When the downward force is suflicient to overcome the contractirlg strength of the snap ring 3-4 (10,000 pounds for example), the latter is released, and the tubular string D and outer member 24 will -move downwardly and cause the chisel teeth 40 to deliver another impact blow against the well packer, breaking it into more fragments. This recocking of the apparatus by elevating the tubular string D and the outer tubular member 24, and then delivering another blo-w by imposition of `a ydownard force on the tubular string and the outer member, can be repeated as often as necessary for the purpose of breaking up the packer parts into sufliciently small particles to be washed away from the drilling region and -out of the Well bore. During the impacting action, drilling lluid can be pumped through the tubular string D and the apparatus A, discharging through the ports S0 to carry the cuttings back to the top of the hole. The impacting action can continue until the apparatus has been disintegrated to the extent at which the lower slips 14 -are released, whereupon the spring legs 62 are again brought up against the ,catch shoulder l19 and the .apparatus elevated to withdraw the remaining lower portion of the well packer from the Vwell casing. If desired, of course, the well packer can be completely disintegrated and -iiushed from the well casing.

In the event of difficulty being encountered in milling up or removing the packer completely, the milling apparatus A can still be withdrawn from the well bore. It is elevated luntil the spring legs 62 engage the catch shoulder '19. Such `engagement and the further engagement of the holding and safety sub 63 against the spring legs will resist rotary movement of the holding and safety sub 63. The tubular string D, outer tubular member 24, mandrel 28 and pilot members 49, including the lower pilot mandrel 56, are rotated. tIn view of the left hand threaded connection 64 between the pilot mandrel 56 and the holding and safety sub 63, a right hand rotation of the mandrel 56 will cause it to elevate itself relative to the holding and safety sub. The shoulder 61 on the pilot mandrel will engage the yflange 60 of the catch sleeve 59 and will then pull the latter upwardly, the feet 69 sliding inwardly along the catch shoulder l19 until they are disposed within the body passage 20, whereupon the lower pilot mandrel 56, safety sub 63 and the spring legs- 6.2 can be moved upwardly through the passage 20 of the packer body and the apparatus withdrawn from the well casing (IFIG. 3).

.For the purpose of insuring that the holding and safety sub l63 will not be comple-tely unthreaded from the pilot mandrel 56, the engagement `of the safety screw 70 with .the lower harige 72 will prevent such action from occu-rring, by limiting the extent of unthreading of the pilot mandrel from the safety sub.

It is, accordingly, apparent that a milling apparatus has been provided which is Very eifective in disintegrating a well packer `or `corresponding barrier set in a well casing `or the like. The milling action or disintegration of the well packer or barrier can occur as the result of a rotary action, or can occur as the result of a jarring action, by causing the chisel teeth 46 to strike impacting or breaking blows upon the packer parts. Such breaking blows will be particularly effect-ive on a well packer of ythe type illustrated, since most of the parts of the latter are made of frangible material, such `as cas-t iron. For that matter, if desired, `a combination of the milling action may occur to disintegrate part of the well packer, supplemented by a repeated jarring action by the chisel portion of the apparatus upon the well packer, or other barrier set in the well casing. It is not necessary for the entire well packer to be disintegrated by the milling apparatus, but as soon-as a sufficient portion has been drilled away, the remaining portion can be retrieved through use of the ca-tch device 59 to 75.

In the event that the complete well packer cannot be removed, the catch device can still be released therefrom through the relative downa-rd threading of the holding and safety sub 63 along the pilot mandrel 56.

The pilot portion 49 of the apparatus maintains the cutter blades 51 and the chisel teeth 4t? properly centered with respect to the packer and the well casing, in order that 4the cutter blades and the chisel teeth are elective for operation only upon the well packer, and cannot engage the well casing itself for the purpose of cut-ting a hole or otherwise damaging the latter.

The invent-or claims:

1. In apparatus for disintegrating a well tool set in a well conduit disposed in a bore hole, the well tool having a .passage therein: supporting meansadapted to be run in the well conduit to the Well tool on a running-in string; cutter means on said supporting means for engagement with said Well tool to disintegrate the same progressively in a downward direction in response to manipulation of the running-in string; 4a pilot secured to said supporting means and adapted for insertion in the `passa-ge to center the cutter means with respect to the -well tool; laterally expandible means on said pilot adapted to =be coupled to the well tool below Ithe point at which said cutter means commenced disintegrating the well tool to elevate the well tool in the well conduit; and means on said pilot Vfor expanding and holding said expandible means laterally outwardly while said cutter means is engaging and disintegrating the well tool.

2. In apparatus for disintegrating a well tool set in a well conduit disposed in a bore hole, the well tool having a passage therein: a mandrel adapted to be connected to a tubular running-in -string and lowered in the well conduit to the well tool; cutter means secured to said mandrel and engageable with the well tool to disintegrate the same progressively in a downward direction in response to rotation of the tubular running-in string and mandrel; a pilot secured to said mandrel for reception in the passage to center the cutter means with respect to the Well tool; means on said pilot adapted to be coupled to .the well tool below the point at which said cutter means commenced disintegra-ting the well tool to elevate the well tool in the well conduit; and means on said pilot for expanding and holding said expandible means laterally outwardly while said cutter means is engaging and`disintegrating the well tool.

Y3. In apparatus for disintegrating a well tool set in a well conduitV disposed in` a bore hole, the well tool having a passage therein and a downwardly facing shoulder surrounding the passage: supporting means adapted to be r-un in the well conduit to the well tool on a running-in string; cutter means on said supporting means for engagement with said well tool to disintegrate the same in response to manipulation of the running-in string; a pilot secured to said supporting means and adapted for insertion in the passage to center the cutter means with respect to the Well tool; catch means including laterally movable spring legs carried by said pilot and ladapted to engage the well tool shoulder; and means on said pilot engaging said legs to hold said legs under said shoulder, whereby elevation of said apparatus and the running-in string elevates the well tool therewith in the well conduit.

4. In apparatus for disintegrating a well -tool set in .a well conduit disposed in a bore hole, the well tool having a passage therein and a downwardly facing shoulder surrounding the passage: supporting means adapted to be run in the well conduit to the Well tool on a running-in string; cutter means on said supporting means for engagement with said well tool to disintegrate the same in response to manipulation of the running-in string; a pilot secured to said supporting means and adapted vfor insertion in thepassage to center the cutter means with respect to the Well tool; catch means including laterally movable spring legs carried .by said pilot and adapted to engage the well tool shoulder; and holding means threaded on said pilot and engaging said legs to hold said legs 'under said shoulder, whereby elevation of said apparatus and the running-in string elevates the well tool therewith in the rwell conduit, rotation of said pilot relative to said holding means feeding said holding means downwardly on said pilot from its position holding said legs under said shoulder.

5. An apparatus for disintegrating a Well tool set in a well conduit disposed in a bore hole, .the well tool having a passage therein: supporting means adapted to be run in the well conduit to the well tool on a running-in string; cutter means on said supporting means for engagement with said well tool to disintegrate the Same in lresponse to manipulation of the running-.in 1 string; a pilot secured/to said supporting means `and adaptedfor insertion in the passage to center. the cutter means .with respect to Ithe well tool; catch means carriedby said pilot and adapted to be coupled tothe well tool below the point at which said cutter means commenced disintegrating the well tool; means on said pilot engageablewith saidcatch means to hold said catch means coupled to said well tool,

whereby elevation of said apparatus and the running-in string elevates the Well tool therewith in the well conduit; and means carried by said pilot for releasing ksaid catch means from coupling relation to the Well tool to permit upward withdrawal of said pilot and catch means through the well tool passage.

6. In lapparatus for ydisintegrating a -well tool set in a well conduit disposed in a bore hole, the well tool having a passage therein: supporting means adapted' to bey run in the well conduit to the well tool on a running-in string; cutter means on said supporting means for engagement with the well tool to disintegrate the same progressively in a downward direction in response to manipulation of the running-in string; a pilot secured to said supporting means and'adapted for insertion in the passage to center the cutter means with respect to the well tool; laterally -expandible means :on said pilot `adapted to be coupled to lthe well tool below the point at which said cutter means commenced disintegrating the well tool to elevate the well tool in the well conduit; and means on said pilot vengaging said expandible means to hold said expandible 7. In apparatus for disintegrating a well tool set in -a well conduit disposed in a bore hole, the well tool having a passage therein: supporting means adapted to be run in the well conduit to the well tool on a running-in string; cutter means on said supporting means for engagement with the well tool to disintegrate the same progressively in a downward direction in response to manipulation of the running-in string; a pilot secured to said supporting means and adapted for insertion in the passage to center the cutter means with lrespect to the well tool; laterally expandi'ble means on said pilot adapted to be coupled to the well tool below the point at which said cutter means commenced disintegrating the -well tool to elevate the well tool in the well conduit; and means engaging said expandible means and constantly urging said expandible means laterally outwardly while said cutter means is engaging and disintegrating the well tool.

8. In apparatus for disintegrating -a well tool set in a well conduit `disposed in a bore hole, the well tool having a passage therein: supporting means :adapted to be -run 'in the well conduit to the well tool on a running-in string; cutter means on said supporting means for engagement with the well tool to `disintegrate the same progressively .in a downward direction in response to manipulation ofthe running-in string; a pilot secured to said supporting means and adapted for insertion in the passage to center the cutter means with respect to the well tool; laterally expandible means on said pilot adapted to be coupled to 4the well tool below the point at which said cutter means commenced disintegrating the well tool to elevate the well tool in the well conduit; means for expanding and holding said expandible means laterally outwardly while said cutter means is engaging and disintegrating the well tool; and means for relatively shifting said expandible means and expanding and holding means to a position permitting uncoupling of said expandible means from the well tool and upward withdrawal of said pilot and expandible means through the well tool passage.

9. In apparatus for disintegrating a well tool set in a well conduit disposed in a bore hole, the well tool having la passage therein and a downwardly facing shoulder surrounding the passage: supporting means adapted to be run in the well conduit to the Well tool on a running-in string; cutter -means on said supporting means for engagement with the well tool to disintegrate the same in lresponse to manipulation of the running-in string; a pilot secured to said supporting means and adapted for insertion in the passage to center the cutter means with respect to the well tool; laterally expandible catch means carried by said pilot and adapted to pass downwardly through the well tool passage to a position below the shoulder before said cutter means initially engages the well tool; and means for expanding said catch means laterally outwardly when positioned below the shoulder and while said cutter means is engaging and disintegrating the well tool, whereby said catch means is adapted for engagement with the shoulder upon elevation of the apparatus and the running-in string to elevate the well tool therewith in the well conduit.

10. In apparatus for disintegrating a well -tool set in a well conduit `disposed in a bore hole, the well tool having a passage therein and a downwardly facing shoulder surrounding the passage: supporting means adapted to be run inthe well conduit to the well tool on a running-in string; cutter means on said supporting means for engagement with the well tool to disintegrate the same in response to manipulation of the running-in string; a pilot secured to said supporting means Iand adapted for inser- .tion in the passage to center the cutter means with respect to the well tool; laterally expandible catch means carried by said pilot and adapted to pass downwardly through the well tool passage to a position below the shoulder before the cutter means initially engages the well tool; and means for expanding said catch means laterally outwardly for engagement with the shoulder upon elevation of the apparatus and the running-in string to elevate the well tool therewith in the well conduit, said expanding means including spring means for shifting said catch means relative .to said pilot and laterally outwardly.

lll. IIn apparatus for disintegrating 1a well tool set in a well conduit disposed in a bore hole, the well tool having la passage therein `and a downwardly facing shoulder surrounding the passage: supporting means adapted to be run in the well conduit to the well tool on a running-in string; cutter means on said supporting means for engagement with the well -tool to disintegrate the same in response -to manipulation of the running-in string; a pilot secured to said supporting means and adapted for insertion in the passage to center the cutter means with respect to the well tool; laterally expandible catch means carried by said pilot and adapted to pass downwardly through the well tool passage to a position below the shoulder before the cutter means initially engages the well tool; means for expanding said catch means laterally outwardly for engagement with the `shoulder upon elevation of the apparatus and the running-in string to elevate the well tool therewith in the well conduit; and means for relatively shifting said catch means and expanding means to permit retraction of said catch means from the shoulder 4and upward withdrawal `of said pilot and catch means through the well tool passage.

l2. In apparatus for disintegrating a well tool set in a well conduit disposed in a bore hole, the iwell tool having a passage therein and a downwardly facing shoulder surrounding the passage: supporting means adapted to be run in the ywell conduit to the well -tool on a running-in string; cutter means on said supporting means for engagement with the well tool to disintegrate the same in response to manipulation of the running-in string; a pilot secured to said supporting means `and adapted for insertion in the passage to center the cutter means with respect to the well tool; catch means including laterally movable spring legs carried by said pilot and adapted to engage the well tool shoulder; means on said pilot engaging said legs to hold said legs under said shoulder, whereby elevation of said apparatus and the running-in string elevates the well tool therewith in the well conduit; and spring means engaging said catch means and urging said catch means downwardly of said pilot to yieldably engage said legs with said holding means.

13. In apparatus for disintegrating ya well tool set in a `well `conduit disposed in a bore hole, the well tool having a passage therein and a downwardly facing shoulder surrounding the passage: supporting means adapted to be run in the lwell conduit to the well tool on a running-in string; cutter means on said supporting means for engagement with the well tool to disintegrate the same in response to manipulation of the running-in string; a pilot secured to said supporting means and adapted for insertion in the passage Ito center the cutter means with respect to the well tool; catch means including laterally movable spring legs carried by said pilot and adapted to engage the well tool shoulder; means on said pilot engaging said legs to hold said legs under said shoulder, fwhereby elevation of said apparatus and the running-in string elevates the well tool therewith in the well conduit; and means for relatively shifting said catch means and holding means to permit retraction of said legs from the shoulder and upward withdrawal of said pilot and catch means through the well tool passage.

14. In apparatus for disintegrating a well tool set in a well conduit disposed in a bore hole, the well tool having a passage therein and a downwardly facing shoulder surrounding the passage: suppor-ting means adapted to be run in the well conduit to the well tool on a running-in string; cutter means on said supporting means for engagement with the 4well tool to disintegrate the same in response to manipulation of the running-in string; a pilot secured to said supporting means `and adapted for insertion in the passage to center the cutter -means with respect .to ythe ywell toolgcatch means including laterally movable spring legs carried by said pilot and adapted to engage the wel-1 tool shoulder, said legs being located below said .cutter means such that said legs are disposed below the the rwell tool therewith inthe welll conduit.

ReferencesCited inthe leofithis patent whereby elevation of said apparatus and the running-n 10 832423 UNITED STATES PATENTS l Robichauxet al. 'Nov. 4, Gean' et a1 Augi l5, 'Baker iJuly 13," Hall -Apr. `29, 

2. IN APPARATUS FOR DISINTEGRATING A WELL TOOL SET IN A WELL CONDUIT DISPOSED IN A BORE HOLE, THE WELL TOOL HAVING A PASSAGE THEREIN: A MANDREL ADAPTED TO BE CONNECTED TO A TUBULAR RUNNING-IN STRING AND LOWERED IN THE WELL CONDUIT TO THE WELL TOOL; CUTTER MEANS SECURED TO SAID MANDREL AND ENGAGEABLE WITH THE WELL TOOL TO DISINTEGRATE THE SAME PROGRESSIVELY IN A DOWNWARD DIRECTION IN RESPONSE TO ROTATION OF THE TUBULAR RUNNING-IN STRING AND MANDREL; A PILOT SECURED TO SAID MANDREL FOR RECEPTION 